Outboard well turbulence

[Rob Johnstone]

Oops. Forgot something. This link takes you to a  cross section sketch of a door, showing down the pull up pull down strings work.

https://www.dropbox.com/s/0iqmja8ensudx7v/Outboard%20doors%20section.jpg?dl=0

[Rob Johnstone]

OOPs Opps. Just realised that the links in the last two post blew the security of my DropBox folders so you'll find they no longer work.

Here are valid links:

To the video of demonstration of the doors
https://www.dropbox.com/s/1anaktfy5bv6v4o/Outboard%20doors.mp4?dl=0

To the sketch section of a door :
https://www.dropbox.com/s/ze59q4ptz89slc7/Outboard%20doors%20section.jpg?dl=0

I think these should be secure.

Sorry

[Graham W]

Here (below) is my wooden solution to outboard well turbulence misery in my BR20. Not quite "bombs away" but still fairly effective and similar to Julian's infill on the previous page. I was prompted to devise this because my Venetian blinds/lamellae were falling to bits and the well turbulence was increasingly noticeable.

Because of the exceptional length of my Torqeedo propellor blades, I need the entire length of the well opening for raising and lowering the motor. On the other hand, when the motor is raised, the well can be closed off completely, with the hinged forward flap lowered and locked down. I have filled in some of the less than watertight gaps around the edges with Sugru.

Probably the most watertight solution was proposed by an erstwhile prolific contributor to the forum. His description is no longer available but I think it involved making a fibreglass cast of the well opening and then using polyurethane foam to fill the cast, with Moss Rubber tape to seal around the edges.  He also had a self-bailer set into the infill, so that water was removed from the well at a faster rate than it could leak in around the edges.

[Julian Swindell]

I have modified my outboard well plug, but don't have photos at the moment. I found that it was really difficult to force the big piece of ply into place against the inflow of water when I was moving. It is surprisingly powerful and it could only be done from one side, due to the engine being in the way. I have cut it in two, with the larger, rear section being fully lift-outable, and the smaller forward section being hinged on one side, so permanently fitted. This arrangement is much easier to close and has an added advantage. When the engine is down, the forward section is left open, but the rear section can be reinserted, which improves flow when motoring. I don't usually bother with it if just motoring out of the marina, but if I am going a long way I often shove it in.

[Julian Swindell]

Just found a photo, which I hope is clearish. Everything is covered in something similar to Coppercoat, which was interesting to apply...

[Graham W]

Nothing quite beats the convenience of the original lamellae.  My wooden infill is a bit of a struggle to install (even with the boat stopped) but has a big grab handle on the top to help the process.  On the other hand, I don't need to swap it about very often.  Like Julian, if I'm only motoring a short distance, I don't bother with it.  All-day sailing is a different matter and when it's fully in place it certainly helps to lift the stern.

[Matthew P]

I have put a lot of effort into streamlining Gladys's bottom.  This has included making a sealed outboard well fairing similar to Julian's but with a 6 mm ply external plate that over the lamellae and fairs in with the battens holding the lamellae in place and a hefty internal plate bolted through the lamellae  to the external plate with a rubber seal around the fiberglass edge - a sort of lamellea sandwich .  The space between the inner and outer plates containing the lamellae filled with water but the volume was small.  This was successful at fairing in the lamellae and more importantly adding buoyancy to the stern that lifted the transom out of the water.  But it took some effort to install each time and negated the use of an outboard - but not having a motor was another ploy for increasing buoyancy in the stern. I have used this system in SailCaledonia and Swallow Boats raids.  Luckliy I have kindly friends willing to give the engine-less Gladys a tow when needed.  Perhaps they will be justifiably less friendly now the nasty competitive motive behind my no-motor policy is known.

The most important thing to be aware of is that sealed outboard wells prevent water from quickly evacuating from the boat if the cockpit swamps.  The tiller hole in the transom provides some escape but not quickly enough if the boat became suddenly and heavily swamped.  I fitted a small removable hatch to quickly drain the outboard well but lying prone facing the stern to open in a crises is probably not a good thing to do.  As I have mentioned before, opening the main ballast tank hatch to move water from the cockpit floor to the ballast tank, where it should probably have been anyway.  If the cockpit swamps and the ballast tank is full then the traditional frightened man bailing with a strong bucket is probably the best option. 

Andrew (the sailing master) suggested a close fitting foam block in the outboard well which is a good idea  but I have not got round to developing a substantial fixing to hold it down and stop it floating out of position.

In cruising mode I thought it would be fun to have a perspex infill so that I can watch the rocks wack my rudder as I hit them.  It was satisfying to make but with an effective seal the disturbed water on top of the perspex made the glass-bottomed boat concept useless except when stopped in very calm water.  Making a seal, with an effective clamp to hold the plate down and yet easy to remove for the outboard to operate has defeated me so far. 

As Graham says, lamellae are the most convenient solution.  After a few years use though they can distort and droop. In desperation I have used a hot airgun to soften centreboard gasket plastic material plastic and to my surprise and delight the laminate meekly returned to its original shape without further persuasion.

Matthew
BR20 Gladys

[Julian Swindell]

Slightly off topic, but I have always felt that Daisy Grace was a bit low at the stern. Certainly,  with more than one crew, there seems to be too much water sloshing up into the cockpit floor from the outboard well. I have tackled this by reducing the ballast in my stern tank (Baycruisers have two tanks, one under the cockpit and one under the fore berth.) At first I did this with a buoyancy bag, shoved in through the tank cover, but this season I have pushed in several slabs of expanded polystyrene, which I haven't tried on the water yet. The idea seems to work, and reduction of ballast had not noticeably affected stability.

[Peter Taylor]

Hi Julian,

Last year, and continuing into the future, I've had a buoyancy bag in the aft ballast tank of a size calculated to displace 26kg of water - being the weight of the 12V lead-acid battery I have situated under the "bridge deck" directly forward of the ballast tank. The effect is to move the cg of the ballast slightly forward and to render the lead acid battery "weightless" as far as calculating the extra weight that I've added to Seatern!  I was a little worried about the bag moving about in the ballast tank, particularly since I sometimes sail with the tank empty, but it stays in place and, as Matt pointed out, it can't move far because of the baffles in the tank.

Having seen how well the buoyacy bag stays in place in the tank I'm wondering about following up your suggestion earlier in this  thread for a air filled bag to seal the outboard well.

Incidentally, I'm also planning to keep the fuel tank installed at the forward end of the side locker in future, again to move weight forward in the boat. Lifting the transom can't be bad and it may even decrease turbulence in the well.
Peter

[Peter Cockerton]

To contribute to the different ideas, I made the installation as shown, in case excess turbulences would slow me down in a race- not the case so far- . It opens and closes well . Obviously it requires space in the well and the engine (Yamaha 5 HP) has to be fully horizontally lifted to flip the cover up or down.
___________________
Catchando Bay (BR#48)

Guy

Have you tried this out on the water yet, does it keep the turbulence down in the well, does the leading edge of the filler lift at all as I guess it's not held down tight to the hull.
The design with the opening and closing controls looks good to me and easy to operate without having to spend time with my head down the well and as a consequence the boat steering all over the place whilst helm unattended. Does the well still fill with water or is it fairly watertight, have you put any method of sealing the infill to the hull when closed.

Appreciate response as i'm looking to copy your idea.

Peter

[Guy Rossey]

Attached yet another solution found as shown at the end of this video:  a sliding cover closes the well on a Thunderbird.

https://www.offcenterharbor.com/videos/ben-seaborns-fabulous-thunderbirds-badass-family-boat-racing-cruising/
___________________
Catchando Bay , BR#48

[Guy Rossey]

Hi Peter,

I read your message today only.
The system is not watertight. It mainly eliminates turbulences. No sealing, water can still come in but remains there with no flushing which is the main purpose. The cover is kept closed by fixing the lines on clam cleats.

Sorry for the late response.
__________________
Catchando Bay BR#48

[Graham W]

Reviving this thread after several years.  It's more of a technical than general question but the thread was originally posted to the latter section.

Having removed my lamellae years ago, I have used a plywood infill to plug the outboard well hole at water level and reduce turbulence, whether motoring or sailing.  A new eProp Spirit electric motor with a wider shaft means that the old infill no longer fits at the front end, so I have made a new one, again from 12mm marine plywood.  I can see quite a lot of daylight around the sides of the cover at its aft end, through which fountains of water and other evidence of turbulence will undoubtedly flow.

My question is, what is the best way of reducing the gaps, which in places are at least a couple of mm wide?  I used Sugru to reduce gaps on my previous cover, which worked reasonably well but was expensive and tended to flake off over time.  I've thought of using Sikaflex or epoxy but don't know how to keep the filler stuck to the edge of the cover while remaining free of the the perimeter of the outboard well opening. Special (or standard) masking tape until the sealant cures?  I've also thought of gluing strips of laminate to the edge of the cover and then sanding them down for a better fit but then will they split off when used roughly?  And I've also considered gluing slot strip around the underside of the edge of the cover.  However, the cover is already quite difficult to manouevre into position under the skeg of the tilted eProp and slot strip would make it even more so.

All suggestions gratefully received.

[Ray S]

Would you not be able to thoroughly coat the edges of the well with a release agent which according to West System videos could be highly burnished Simoniz wax and then use epoxy filler around the edges of the plywood infill? Of course you would have to be careful the shape of the set filler doesn't lock the plywood infill in place.

Might be wanting to do something similar eventually so interested to see how you get on!

BRe 047 'Whimbrel'

[Michael Rogers]

Graham

Not being the proud owner of a hole in the bottom of my boat (filled, part time only, by an outboard), I can only generalise. There are now widely available (e.g. see Amazon) 'cyanoacrylate activators' which, used with superglue, enable almost everything to be glued to almost everything else. And they work. Last year I wrote up (somewhere else in the forum) using one of the first available in the UK, which actually came from Poland, to stick thin PTFE sheet to polypropylene webbing - two of the most previously no-no substances you could think of for gluing together purposes. A year on, they remain firmly fused to each other, and look to be inseparable for the long term, bless them. A few weeks ago I used 'Xpert Activator' + superglue to stick rather thicker PTFE sheet to two-pot-painted surfaces when re-assembling my repainted kick-up rudder: again, perfect result, and a rolls-royce smoothness as the rudder blade swings up and down.

Using this new glue technology, I was wondering whether you could find some sort of pliable plastic sheet to stick round the edge of your cover, slightly over-filling the hole and bending upwards round the edges, to keep most of the splash below the cover. The right degree of bendability would be critical. It might work even better if you reduced the size of the infill to leave a deliberate gap, now filled with your flap-valve material and even with a plastic edging strip along the free edge to improve the seal. The point is that you can now stick almost anything to anything else.

Just a thought, hope it helps. I think 'gluing' has been quietly revolutionised, and the possibilities are endless.

Michael R